The San Jose Earthquakes played through a tie that felt a little bit like a defeat on Saturday, taking an early lead but allowing a second-half goal to D.C. United rookie Andy Najar before finishing up deadlocked at 1-1.

Even worse, it was a tie that might lead to a greater loss for the Quakes. Bobby Convey, unquestionably San Jose’s best overall performer in 2010, played the entire match despite reinjuring the ribs on his left side to the point where he was spitting up blood in the first half.

Convey went down a few seconds after throwing himself in front of an attempted cross from United right back Devon McTavish in the 22nd minute. The ball smacked Convey on his exposed rib cage, the same spot where he was originally elbowed against FC Dallas on June 5.

“I was trying to play through it, but I was coughing up blood, and obviously, that’s not good,” said Convey, who said he’s slated for X-rays either Sunday or Monday.

Convey went to ground moments after being struck by the ball and looked as though he would have to be replaced, but after some discussion stayed in -- and he twice almost clinched a win for San Jose.

In the 26th minute, after D.C. goalkeeper Troy Perkins came out of goal but was unable to fully clear a Steve Beitashour cross, Convey yanked his rebound shot wide right. Then in the 69th, he laid out a beautiful ball to the near post for Arturo Alvarez to slot home. But Alvarez, trying to guide the ball to the far post, didn’t get enough of a touch and it slid harmlessly out of bounds.

“That wasn’t our best game, I don’t think,” Convey said. “We played much better in Salt Lake [tying the defending champions 0-0 on June 25] and we’ve played much better before at home. If I finish my chance in the first half, and then obviously Arty in the second half, the game’s put away, basically.”

After struggling to find his place with the Quakes in his return to MLS last season, Convey has taken over as San Jose’s de facto leader, dishing out seven assists (second in the league behind Landon Donovan) and displaying tireless box-to-box tenacity.

“Bobby’s a huge cog in our system,” forward Chris Wondolowski said. “It’s not only the service, it’s his workrate. That guy’s everywhere.”

Even with Convey at 100 percent, San Jose still faces mounting questions about their offense. The Quakes have been limited to five goals in their last seven matches, tailing off markedly after scoring 11 in their first half-dozen games.

“I don’t think I pulled my weight or carried the team like I usually do, and that makes a difference,” Convey said. “Sometimes you have to get bailed out by finishing your couple of chances, and we didn’t finish. They had their one good chance and they scored, and we had three or four and we only scored one.”

San Jose is excelling on set pieces, such as the 16th-minute corner kick which led to Ike Opara’s third MLS goal and a 1-0 Quakes lead. The rookie center back scooped up a 50-50 ball contested by teammate Ramiro Corrales and D.C.’s Juan Manuel Pena (who had been marking Opara) and squeezed it between Perkins and the near post. Of 16 San Jose goals this season, five have come from corners.

But in the run of play, San Jose either couldn’t shoot straight -- see Convey’s miss and Alvarez’s near-whiff -- or were snuffed out by Perkins, who finished with four saves. The United goalkeeper’s highlights included slamming the door on Ramiro Corrales at the back post in the 51st minute after a Brandon McDonald throw-in initially eluded him, and turning aside a 10-yard blast from rookie Omar Jasseh in the 88th minute.

“Their goalie made some game-changing saves,” Opara said. “That one with Rams at the back stick was huge. If we get that one, we can see the game out, I think.”

Instead, San Jose (5-4-4), who haven’t won at home since May 8, were left to rue a lost pair of potential points that could loom large at season’s end. When a playoff-bound team hosts an opponent that is tied for the fewest points in the league, a come-from-ahead draw is not usually the result.

“Obviously, we’re disappointed to not win at home,” coach Frank Yallop said. “You’re always on a bit of a tightrope when it’s one-nil. It’s just unfortunate we couldn’t stick that second goal in.”

Geoff Lepper covers the Earthquakes for MLSsoccer.com. He can be reached at sanjosequakes@gmail.com, and on Twitter @sjquakes.